Field
The disclosed concept pertains generally to electrical switching apparatus such as for example, circuit breakers. The disclosed concept also pertains to operating handle assemblies for electrical switching apparatus. The disclosed concept further relates to trip cams for operating handle assemblies.
Background Information
Electrical apparatus, such as electrical switching apparatus or electrical meters used in power distribution systems, are often mounted on or within an electrical enclosure (e.g., without limitation, a panelboard; a load center; a meter breaker panel) either individually or in combination with other electrical meters or switchgear (e.g., without limitation, circuit switching devices and circuit interrupters such as circuit breakers, contactors, motor starters, motor controllers and other load controllers). Such circuit breakers are used to protect electrical circuitry from damage due to a trip condition, such as, for example, an overcurrent condition, an overload condition, an undervoltage condition, a relatively high level short circuit or fault condition, a ground fault or arc fault condition.
Molded case circuit breakers, for example, include at least one pair of separable contacts which are operated either manually by way of a handle disposed on the outside of the case, or automatically by way of a trip unit in response to the trip condition. Generally, the trip unit includes a cradle assembly which is operable between a latched configuration during normal circuit breaker operation, and an unlatched position in which the separable contacts are tripped open, in response to the trip condition.
Known circuit breakers employ relatively large mechanism spring forces to assure adequate contact pressures. However, these forces generate relatively significant friction at component interfaces. In many situations, this friction significantly restricts the movement of circuit breaker components, potentially causing the operating handle to become undesirably stuck in an unintended position.
There is thus room for improvement in electrical switching apparatus, and in operating handle assemblies and trip cams therefor.